Cylinder head gaskets of engines and exhaust manifold gaskets for an automobile, a motorcycle and the like are exposed to repeated pressure fluctuations under a high temperature, a high pressure, and a high vibration that are peculiar to the engines. Among these, the cylinder gasket for an automobile engine receives a high pressure in the compression stroke, and thus is necessarily in contact with both the contact materials with a high contact pressure (surface pressure) for retaining the sealing property. The metal gasket used in an engine or an exhaust gas flow path generally has a bead having a constant height (i.e., a continuous ridge) formed through bead forming by pressing, for ensuring the sufficient contact pressure. The metal gasket of this type is used by pressing the apex of the bead ridge (which is hereinafter referred to as a bead apex) onto a contact material for ensuring the high sealing property, and therefore necessarily has a high strength and high fatigue characteristics in use.
A work-hardening metastable austenitic stainless steel (such as SUS301 series) has been often used in the gasket applied to an automobile engine and an exhaust gas flow path thereof. The steel of this type achieves a high strength through formation of deformation induced martensite by cold rolling. However, the cold rolling reduction ratio is necessarily increased for enhancing the strength level. The increase of the cold rolling reduction ratio may be a factor decreasing the toughness, the fatigue resistance characteristics, and the workability. PTLs 1 and 2 describe metastable austenitic stainless steels that are improved in these characteristics. There has been a martensitic stainless steel as a material having a strength that is enhanced without the increase of the cold rolling reduction ratio. PTL 3 describes the application of a martensitic steel types to a gasket.